Conventional non-contact power supply systems are known in the art, which supply electric power from a power supply coil of a non-contact power supply device to a power receiving coil of a power supply receiving device by utilizing an electromagnetic induction phenomenon. Such non-contact power supply systems are inconvenient because the power supply coil and the power receiving coil need to be positioned with each other.
In view of this, a technique disclosed in Patent Literature 1 is known in the art, for example. According to the technique disclosed in Patent Literature 1, a plurality of power supply coils of the power supply device are arranged in a matrix pattern. Then, the position of the power supply receiving device is detected, and a power supply coil located facing the power supply receiving device is driven to supply power to the power supply receiving device.
Therefore, a user can simply place the power supply receiving device over the power supply device, without accurately positioning the power supply coil and the power receiving coil with each other, to enable non-contact power supply from a power supply coil located facing the power receiving coil of the power supply receiving device.
In order to enable power supply only for particular power supply receiving devices, techniques have also been known in the art in which the power supply receiving device transmits an authentication signal to the power supply device so that power supply is enabled only when the authentication succeeds (see, for example, Patent Literature 2).
However, with the technique disclosed in Patent Literature 2, the power supply receiving device needs to transmit an authentication signal to the power supply device in order to authenticate the power supply receiving device. Moreover, required electric power, which is electric power needed for the power supply receiving device to operate to transmit the authentication signal to the power supply device, needs to be supplied from the power supply device to the power supply receiving device.
On the other hand, where power supply coils are arranged in a matrix pattern, and one of the power supply coils located facing the power receiving coil of the power supply receiving device (power supply target device) is selected and driven, as in the technique disclosed in Patent Literature 1, the position of the selected power supply coil and the position of the power receiving coil may be misaligned with each other. When the position of the power supply coil and the position of the power receiving coil are misaligned with each other, the electric power to be supplied from the power supply device to the power supply receiving device decreases. Therefore, the electric power supplied from the power supply device to the power supply receiving device becomes less than the required electric power. As a result, the power supply receiving device may possibly fail to transmit an authentication signal to the power supply device, thereby failing the authentication.